CoNi bimetallic metal–organic framework and gold nanoparticles-based aptamer electrochemical sensor for enrofloxacin detection

In this study, an electrochemical aptasensor was established for the ultrasensitive detection of enrofloxacin (ENR) based on a CoNi-based metal–organic framework (MOF) and gold nanoparticles (AuNPs). Co-MOF, Ni-MOF, and CoNi-MOF were optimized by characterization techniques like scanning electron microscope (SEM), Fourier-transform infrared spectrophotometer (FT-IR), and X-ray diffraction (XRD). The optimal CoNi-MOF has waxberry-like structure, mixed metal valences, and π-conjugated structure, which show biocompatibility, high hydrophilicity, and good electrochemical stability. In order to enhance the electrochemical performance of the sensor, electrodeposition of AuNPs was used to improve conductivity and increase the load of sulfhydryl group-modified aptamer (Apt) by Au-S bond. The electrochemical behavior was studied by cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The Apt/AuNPs/CoNi-MOF/GCE exhibits an extensive detection range of 1 × 10−3 pg·mL−1 to 1 × 105 pg·mL−1 (S/N = 3) and a detection limit of 3.3 × 10−4 pg·mL−1 for ENR under optimal conditions. The arranged sensor demonstrates a high sensitivity, satisfactory reproducibility, and long-time stability. Furthermore, the obtained sensor reveals a high practical prospect for the sensitive detection of ENR in meat samples.